The Belgian winger finally left Manchester United in the summer after recent seasons spent either on the bench or out on loan.
When he first broke on to the scene under David Moyes at the age of 18, much was expected of the talented attacker.
But that failed to materialise, with Januzaj falling out of favour with van Gaal then failing to really impress when Jose Mourinho took over the club.
While it’s Mourinho who sold Januzaj to Sociedad in a £9.8million deal, the Belgian blames van Gaal for what happened to him at Old Trafford – and has sarcastically promised to dedicate his next goal to the Dutch manager.
“I don’t want to talk about him [Van Gaal], but everyone knows how many problems I had with him.
“We didn’t have the best of rapports. It wasn’t easy, it’s very frustrating and difficult when you are in a situation like that.”
So Januzaj isn’t a fan of the eccentric Dutch manager?
Now Januzaj is preparing to make his first appearance for Sociedad when they play Villarreal in La Liga on Friday.
And we’ll certainly be watching for that van Gaal tribute.